Switchable support elements are known from the prior art in which coupling of an at least one coupling piston arranged in the inner element is effected radially outwards into a bore of the housing. It is thus clear that in such a configuration very high demands must be made of positional exactitude to enable an extension of the coupling piston in coupling direction for achieving coupling (s. DE 101 22 373 A1). Besides this, no clear measures for realizing a simple radial inner stop position of the coupling element are provided by this document.
In other known switchable valve train members, the inner peripheral surface of the housing comprises an annular groove into which the at least one coupling piston must be displaced. This annular groove weakens the wall of the housing, so that, where appropriate, the housing must be made with a thicker wall. In addition, because the annular groove extends on the entire circumference, the complexity and costs of making the annular groove in large series are unduly high (transverse feed etc.).